Besides focusing on individuals, start thinking of the problems.
FOOD: The higher up in the mountains you are, the less resources you have for food. So when was the large bulk food source area and where is the next one? Figure you need a minimum of one pound of food per person per day. That's five tons. Also identify where there will be enough area for ten thousand people to cook food.
WATER: Again, the higher into the mountains you go, the less sources of water that there are. Assuming one gallon of water per day per man. You need ten thousand gallons of water per day. Tanker trucks on the highway don't quite get up to that in capacity, and the average pool might have 3,000 gallons. By the way, each one of those gallons weighs eight pounds. Take your five tons of food and add in another 40 tons. Remember that carrying all this food and water costs additional calories.
SPEED: I'm assuming that only one person at a time can walk on the trail, i.e., no two or more abreast. Let's assume you have a walking speed of two miles per hour, and the bottleneck portion of the trail is one mile long. So the first person starts walking, taking half an hour to get over the trail. Next person starts four feet behind the first person (measured big toe to big toe). The last person leaves 7.7 hours later.
In other words, bare minimum is this is going to take all day to travel one mile, and during most of the day, you're fighting force is going to be badly divided. In other words, a high risk situation. And add into the time problem everything that goes wrong. When marcher number 34 trips, and wastes a minute getting up and going again, guess what that does to everyone behind him? You're going to have gridlock and the 2 mph average speed is going to disappear quickly.
Probably better figure on two days, at least, to get everybody over the pass. And don't forget to figure in the injury factor. You know one idiot, at a minimum, is going to break his leg. If a tenth of percent of the hikers get injured, you've got ten people to deal with. And how are they going to get over the pass?
Getting tense about how to do this in your book now?
Best of luck,
Jim Clark-Dawe